After two years of Mars enthusiasts asking, “Are we there yet?” the mission managers for NASA’s Curiosity rover can finally yell back, “Yes, we’re there!”

The Curiosity rover has reached the destination where it will begin its main science investigations, the base of a three-mile-high mountain that the science team has named Mount Sharp. As the rover makes it way up the mountain, it will cross layers of rock that contain clues to the early geological and environmental history of Mars when it was warmer and wetter.

“We are here to tell everyone that the next phase of research on Mars for Curiosity can now begin,” James L. Green, the director of NASA’s planetary science division, said during a telephone news conference on Thursday.

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One year ago, the rover's arrival on Mars ushered in a new era of exploration. Since then, it has been inching toward a mountain that could yield fascinating insights.Published OnAug. 5, 2013CreditCreditNASA

The rover landed in August 2012 within the 96-mile-wide Gale Crater after an eight-month cruise from earth. John P. Grotzinger, the project scientist for the mission, characterized the drive of the past two years as a second cruise phase. “The science is all in front of us,” he said. “But for this moment, we should be celebrating the engineering accomplishments of this mission.”

Curiosity did conduct some science measurements soon after it landed, fulfilling one of its central objectives: showing that the crater was once an ancient lake that could have been habitable for microbes, if any microbes existed. Now, the scientists are hoping to find carbon-based compounds preserved within the rocks that could have served as the building blocks for life.

The trip to Mount Sharp has taken longer than expected, partly because of the diversion for scientific measurements and because Curiosity needs to be driven with some care, to avoid sharp rocks of the kind that have damaged its wheels and soft sand dunes that might ensnare it.

The mission, and Dr. Grotzinger in particular, came under criticism during a review for its proposal for two years of additional financing beyond its original two-year span. The review panel, composed of outside experts hired by NASA, ranked it the lowest of the seven NASA proposals it looked at. Though the panel ultimately voted to extend Curiosity’s mission, its members expressed concern that the mission was underperforming for its $2.5 billion price tag and that the mission team was putting too much emphasis on driving and not enough on conducting scientific research.

Dr. Green focused on the panel’s overall positive conclusion — that all of the extended missions were cost-effective and productive — and played down the negatives. “To me, the top recommendation is how important these missions are as we move forward,” he said. For the 2015 fiscal year, the Curiosity mission will cost $59.4 million to operate.

Dr. Grotzinger also presented the results of the rover’s most recent attempt at drilling a rock that the scientists call Bonanza King, which after being dusted off was found to be a gray-green color, rather than the usual Mars red. The effort failed, because the rock proved to be not safe to drill. “The rock started to move,” he said. “It jumped around.”

Other instruments found the rock to have a high silicon content, which Dr. Grotzinger said was an indication that it had been altered by water.

The rover is now headed to an outcrop called Pahrump Hills at the base of Mount Sharp and should arrive in a week or two. There, the mission scientists expect to find a suitable rock to drill.

A version of this article appears in print on , on Page A19 of the New York edition with the headline: After a Two-Year Trek, NASA’s Mars Rover Reaches Its Mountain Lab. Order Reprints | Today’s Paper | Subscribe